1. Field of the Invention
The present invention relates generally to apparatus and a method for decomposing halogenated compounds, and more specifically to apparatus and a method for the low temperature destruction of halogenated hydrocarbons.
2. Background of the Invention
The persistence of halogenated compounds in the environment continues to pose ecological and health problems. These compounds are of both the aliphatic and aromatic variety and are associated with aspects of electronic component fabrication, dielectric applications, metal finishing industries, paint production, plastics production/recycling, oil production industries, and other industrial applications. Such compounds include the polyhalogenated aromatic- and polyaromatic-compounds (e.g., the polychlorinated biphenyls) and the alkyl halides (e.g., polyhalogenated ethylene, chloroform, carbon tetrachloride, methylene chloride, and others).
A myriad of disposal techniques have been studied in attempts to degrade or otherwise isolate these compounds, including burial, incineration, photodecomposition, adsorption, and chemical degradation. Generally, methods to degrade halogenated materials into innocuous products have had limited success due to stringent operating parameters associated with those methods. For example, the addition of alkaline solutions into a mixture containing polychlorinated biphenyls (PCBs) with alcohol dispersing agents, has been attempted to decompose halogenated material (U.S. Pat. No. 4,351,978). This technique, which utilizes Raney catalysts, requires establishing and maintaining alkaline conditions so as to maintain the reactive capabilities of the catalyst. The technique also requires the addition of gaseous hydrogen to effect substitution of the halogen moieties. Another process (U.S. Pat. No. 4,931,167) requires the use of Lewis acid catalysts in anhydrous conditions, and at temperatures in excess of 300.degree. C.
Thermal degradation is the method allowed by the U.S. Environmental Protection Agency for fluids which contain more than 500 parts per million (ppm) polychlorobiphenyls (PCBs). However, much criticism has been directed towards thermal incineration as an uneconomical means of destroying these materials. The many shortcomings of utilizing typical incineration methods include high capital costs of constructing large-bed reaction zones, and the high operating costs of maintaining molten salt systems and incineration systems at 1100.degree. C. and 2600.degree. C., respectively. The need for large beds and long residence times to effect conversion of halogenated materials to innocuous salts or gaseous decomposition products is directly related to the high costs of these processes. Limited incinerators currently exist for disposing of halogenated waste so that toxic chemicals must be stockpiled prior to disposal.
A need exists in the art for a low cost, highly efficient alternative technology to conventional halogenated hydrocarbon incineration. Such technology should operate at relatively lower temperatures, be able to economically dispose of hazardous waste, and use recyclable reaction materials. Also, these recyclable materials should be commercially available. Such a system would ameliorate the problems and costs associated with stockpiling halogenated waste material and would also facilitate bench-top disposal capability so as to allow disposal of toxics where they are normally produced, used, or discarded.